Physically it should drop right in. Although you may need to trim the top flange of the frame a little to clear the exhaust manifolds or headers. Which trans are you going to use? There is quite a bit to swapping in a LSx series engine, and making it all function. You will probably get more difinitive answers over n the LSx swap section. Those guys have been there done that. Here you go
http://www.67-72chevytrucks.com/vboa...ysprune=&f=206